Expression pattern and prognostic value of circadian clock genes in pancreatic adenocarcinoma

The circadian clock as a potential biomarker and therapeutic target in pancreatic cancer

Pancreatic cancer (PC) has a very high mortality rate globally. Despite ongoing efforts, its prognosis has not improved significantly over the last two decades. Thus, further approaches for optimizing treatment are required. Various biological processes oscillate in a circadian rhythm and are regulated by an endogenous clock. The machinery controlling the circadian cycle is tightly coupled with the cell cycle and can interact with tumor suppressor genes/oncogenes; and can therefore potentially influence cancer progression. Understanding the detailed interactions may lead to the discovery of prognostic and diagnostic biomarkers and new potential targets for treatment. Here, we explain how the circadian system relates to the cell cycle, cancer, and tumor suppressor genes/oncogenes. Furthermore, we propose that circadian clock genes may be potential biomarkers for some cancers and review the current advances in the treatment of PC by targeting the circadian clock. Despite efforts to diagnose pancreatic cancer early, it still remains a cancer with poor prognosis and high mortality rates. While studies have shown the role of molecular clock disruption in tumor initiation, development, and therapy resistance, the role of circadian genes in pancreatic cancer pathogenesis is not yet fully understood and further studies are required to better understand the potential of circadian genes as biomarkers and therapeutic targets.

Developments on tumour site-specific chrono-oncology towards personalised treatment

Research into chronotherapy has seen notable developments over the past decades, with a clear focus on the identification of circadian clock genes as potential treatment targets. Moreover, new factors are investigated, such as gender and the role of cancer stem cells in influencing the outcome of chronomodulated treatments. These factors could add to the arsenal of parameters that assist with patient stratification and treatment personalisation. Literature analysis showed that certain anatomical sites received more attention and the associated studies reported clinically significant results, even though some findings are contradictory. The aim of this work was to review the existing studies on chrono-oncology using a tumour site-specific approach and to highlight the status of research in various cancers. Inconsistencies in data reporting, the nature of the studies and the highly heterogeneous patient characteristics, highlight the need for well-designed randomised controlled trials to elucidate the real potential of chronotherapy in oncology.